package com.hualidianping.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hualidianping.dto.Result;
import com.hualidianping.entity.SeckillVoucher;
import com.hualidianping.entity.VoucherOrder;
import com.hualidianping.mapper.VoucherOrderMapper;
import com.hualidianping.service.ISeckillVoucherService;
import com.hualidianping.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hualidianping.utils.RedisIdWorker;
import com.hualidianping.utils.SimpleRedisLock;
import com.hualidianping.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    //解决事务的第二种方法
    @Resource
    private VoucherOrderServiceImpl voucherOrderServiceImpl;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    //代理对象,解决事务
    private IVoucherOrderService proxy;

    //
    static {
        SECKILL_SCRIPT=new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    //异步处理线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR= Executors.newSingleThreadExecutor();
    //在类初始化之后执行，因为当这个类初始化好了之后，随时都是有可能要执行的
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    //处理订单的任务
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while (true){
                try {
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create("stream.orders", ReadOffset.lastConsumed())
                    );
                    //2.判断订单消息是否为空
                    if(list==null||list.isEmpty()){
                        //如果为null，说明没消息，继续下一次循环
                        continue;
                    }
                    //解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    //3.创建订单，事务化
                    handleVoucherOrder(voucherOrder);
                    //4.确认消息XACK
                    stringRedisTemplate.opsForStream().acknowledge("stream.orders","g1",record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常",e);
                    handlePendingList();
                }
            }
        }
        private void handlePendingList(){
            while (true) {
                try {
                    // 1.获取pending-list中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create("stream.orders", ReadOffset.from("0"))
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明没有pending-list没有异常消息，结束循环
                        break;
                    }
                    // 解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    //3.创建订单，事务化
                    handleVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK
                    stringRedisTemplate.opsForStream().acknowledge("stream.orders", "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单pending-list异常", e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        }
    }
    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        long orderId=redisIdWorker.nextId("order");
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(), String.valueOf(orderId)
        );
        //2.判断结果是否为0
        int r=result.intValue();
        if(r!=0){
            //2.1不为0，代表没有购买资格
            return Result.fail(r==1?"库存不足":"不能重复下单");
        }
        //3.返回订单id
        return Result.ok(orderId);
    }

    //加锁
    private void handleVoucherOrder(VoucherOrder voucherOrder){
        //1.获取用户
        Long userId = voucherOrder.getUserId();
        //2.创建锁对象
        RLock lock=redissonClient.getLock("lock:order"+userId);
        //3.获取锁
        boolean isLock = lock.tryLock();
        //4.判断是否获取锁成功
        if(!isLock){
            //获取锁失败，返回错误或重试
            log.error("不允许重复下单");
            return;
        }
        try {
            voucherOrderServiceImpl.createVoucherOrder(voucherOrder);
        }finally {
            //释放锁
            lock.unlock();
        }

    }

    //数据库事务
    @Override
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();
        // 5.1.查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        // 5.2.判断是否存在
        if (count > 0) {
            // 用户已经购买过了
            log.error("不允许重复下单！");
            return;
        }
        // 6.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock - 1
                .eq("voucher_id", voucherId).gt("stock", 0) // where id = ? and stock > 0
                .update();
        if (!success) {
            // 扣减失败
            log.error("库存不足！");
            return;
        }
        // 7.创建订单
        save(voucherOrder);
    }


    /*
        //lua脚本实现异步秒杀
    @Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        //2.结果是否为0
        int r=result.intValue();
        if(r!=0){
            //2.1.不为0，代表没有购买资格
            return Result.fail(r==1?"库存不足":"不能重复下单");
        }
        //2.2.为0，有购买资格，把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.3.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //2.4.用户id
        voucherOrder.setUserId(userId);
        //2.5.代金券id
        voucherOrder.setVoucherId(voucherId);
        //2.6.放入阻塞队列
        orderTasks.add(voucherOrder);
        //3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        return Result.ok(orderId);
    }
    static {
        SECKILL_SCRIPT=new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill0.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    //异步处理线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR= Executors.newSingleThreadExecutor();
    //在类初始化之后执行，因为当这个类初始化好了之后，随时都是有可能要执行的
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    private BlockingQueue<VoucherOrder> orderTasks=new ArrayBlockingQueue<>(1024*124);
    // 用于线程池处理的任务
    // 当初始化完毕后，就会去从对列中去拿信息
    private class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while (true){
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                }catch (Exception e){
                    log.error("处理订单异常：",e);
                }
            }
        }

        private void handleVoucherOrder(VoucherOrder voucherOrder) {
            //1.获取用户
            Long userId = voucherOrder.getUserId();
            // 2.创建锁对象
            RLock lock = redissonClient.getLock("lock:order:" + userId);
            // 3.尝试获取锁
            boolean isLock = lock.tryLock();
            // 4.判断是否获得锁成功
            if (!isLock) {
                // 获取锁失败，直接返回失败或者重试
                log.error("不允许重复下单！");
                return;
            }
            try {
                //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy.createVoucherOrder(voucherOrder);
            } finally {
                // 释放锁
                lock.unlock();
            }
        }
    }
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();
        // 创建锁对象
        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
        // 尝试获取锁
        boolean isLock = redisLock.tryLock();
        // 判断
        if (!isLock) {
            // 获取锁失败，直接返回失败或者重试
            log.error("不允许重复下单！");
            return;
        }

        try {
            // 5.1.查询订单
            int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            // 5.2.判断是否存在
            if (count > 0) {
                // 用户已经购买过了
                log.error("不允许重复下单！");
                return;
            }

            // 6.扣减库存
            boolean success = seckillVoucherService.update()
                    .setSql("stock = stock - 1") // set stock = stock - 1
                    .eq("voucher_id", voucherId).gt("stock", 0) // where id = ? and stock > 0
                    .update();
            if (!success) {
                // 扣减失败
                log.error("库存不足！");
                return;
            }
            // 7.创建订单
            save(voucherOrder);
        } finally {
            // 释放锁
            redisLock.unlock();
        }
    }
     */


    /*
        //redisson锁
    //一人一单,悲观锁对插入操作加锁，乐观锁对更新操作加锁，解决超卖，实现过期自动续期，redisson锁也可重入
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀尚未开始！");
        }
        // 3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀已经结束！");
        }
        // 4.判断库存是否充足
        if (voucher.getStock() < 1) {
            // 库存不足
            return Result.fail("库存不足！");
        }
        Long userId = UserHolder.getUser().getId();
        //创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //获取锁,线程无等待时间
        boolean isLock = lock.tryLock();
        //锁结构为lock:order:userId==>tomcat的UUID-threadId
        //判断是否获取锁成功
        if(!isLock){
            //获取锁失败，返回错误
            return Result.fail("不允许重复下单");
        }
        try {
            return voucherOrderServiceImpl.createVoucherOrder(voucherId);
        }finally {
            lock.unlock();
        }
    }

    @Transactional
    public  Result createVoucherOrder(Long voucherId) {
        //5.一人一单逻辑
        Long userId = UserHolder.getUser().getId();
        //5.1查询订单
        int count= query().eq("user_id",userId).eq("voucher_id", voucherId).count();
        //5.2判断是否存在
        if(count>0){
            //用户已经购买过了
            return Result.fail("用户已经购买过一次！");
        }
        //6.扣减库存
        boolean success = seckillVoucherService.update().setSql("stock=stock-1")
                .eq("voucher_id", voucherId).gt("stock",0).update();
        if(!success){
            //扣减库存
            return Result.fail("库存不足！");
        }
        //7.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //7.1.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //7.2.用户id
        voucherOrder.setUserId(userId);
        //7.3.代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        return Result.ok(orderId);
    }
     */


    /*
//分布式锁
    //一人一单,悲观锁对插入操作加锁，乐观锁对更新操作加锁，解决超卖
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀尚未开始！");
        }
        // 3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀已经结束！");
        }
        // 4.判断库存是否充足
        if (voucher.getStock() < 1) {
            // 库存不足
            return Result.fail("库存不足！");
        }
        Long userId = UserHolder.getUser().getId();
        //创建锁对象
        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        //获取锁
        boolean isLock = lock.tryLock(2);
        //锁结构为lock:order:userId==>tomcat的UUID-threadId
        //判断是否获取锁成功
        if(!isLock){
            //获取锁失败，返回错误
            return Result.fail("不允许重复下单");
        }
        try {
            return voucherOrderServiceImpl.createVoucherOrder(voucherId);
        }finally {
            lock.unlock();
        }
    }

    @Transactional
    public  Result createVoucherOrder(Long voucherId) {
        //5.一人一单逻辑
        Long userId = UserHolder.getUser().getId();
        //5.1查询订单
        int count= query().eq("user_id",userId).eq("voucher_id", voucherId).count();
        //5.2判断是否存在
        if(count>0){
            //用户已经购买过了
            return Result.fail("用户已经购买过一次！");
        }
        //6.扣减库存
        boolean success = seckillVoucherService.update().setSql("stock=stock-1")
                .eq("voucher_id", voucherId).gt("stock",0).update();
        if(!success){
            //扣减库存
            return Result.fail("库存不足！");
        }
        //7.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //7.1.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //7.2.用户id
        voucherOrder.setUserId(userId);
        //7.3.代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        return Result.ok(orderId);
    }
     */

/*
    //一人一单,悲观锁对插入操作加锁，乐观锁对更新操作加锁，解决超卖
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀尚未开始！");
        }
        // 3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀已经结束！");
        }
        // 4.判断库存是否充足
        if (voucher.getStock() < 1) {
            // 库存不足
            return Result.fail("库存不足！");
        }
        Long userId = UserHolder.getUser().getId();
        synchronized (userId.toString().intern()){
            //获取代理对象(事务)
            return voucherOrderServiceImpl.createVoucherOrder(voucherId);
        }
    }

    @Transactional
    public  Result createVoucherOrder(Long voucherId) {
        //5.一人一单逻辑
        Long userId = UserHolder.getUser().getId();
        //5.1查询订单
        int count= query().eq("user_id",userId).eq("voucher_id", voucherId).count();
        //5.2判断是否存在
        if(count>0){
            //用户已经购买过了
            return Result.fail("用户已经购买过一次！");
        }
        //6.扣减库存
        boolean success = seckillVoucherService.update().setSql("stock=stock-1")
                .eq("voucher_id", voucherId).gt("stock",0).update();
        if(!success){
            //扣减库存
            return Result.fail("库存不足！");
        }
        //7.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //7.1.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //7.2.用户id
        voucherOrder.setUserId(userId);
        //7.3.代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        return Result.ok(orderId);
    }
 */


/*
    //乐观锁解决超卖
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀尚未开始！");
        }
        // 3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀已经结束！");
        }
        // 4.判断库存是否充足
        if (voucher.getStock() < 1) {
            // 库存不足
            return Result.fail("库存不足！");
        }
        //5，扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock= stock -1")
                .eq("voucher_id", voucherId).gt("stock",0).update();
        if (!success) {
            //扣减库存
            return Result.fail("库存不足！");
        }
        //6.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        // 6.1.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 6.2.用户id
        Long userId = UserHolder.getUser().getId();
        voucherOrder.setUserId(userId);
        // 6.3.代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        return Result.ok(orderId);
    }
 */


/*
//存在超卖问题
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀尚未开始！");
        }
        // 3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀已经结束！");
        }
        // 4.判断库存是否充足
        if (voucher.getStock() < 1) {
            // 库存不足
            return Result.fail("库存不足！");
        }
        //5，扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock= stock -1")
                .eq("voucher_id", voucherId).update();
        if (!success) {
            //扣减库存
            return Result.fail("库存不足！");
        }
        //6.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        // 6.1.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 6.2.用户id
        Long userId = UserHolder.getUser().getId();
        voucherOrder.setUserId(userId);
        // 6.3.代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        return Result.ok(orderId);
    }
 */

}
